Objective We evaluated the characteristics of HIV-1 molecular transmission clusters (MTCs) in 1890 newly diagnosed individuals infected with non-B subtypes between 2005 and 2017 in Italy.
Methods Phylogenetic analyses were performed on pol sequences to characterise subtypes/circulating recombinant forms and identify MTCs. MTCs were divided into small (SMTCs, 2–3 sequences), medium (MMTCs, 4–9 sequences) and large (LMTCs, ≥10 sequences). Factors associated with MTCs were evaluated using logistic regression analysis.
Results 145 MTCs were identified and involved 666 individuals (35.2%); 319 of them (16.9%) were included in 13 LMTCs, 111 (5.9%) in 20 MMTCs and 236 (12.5%) in 112 SMTCs. Compared with individuals out of MTCs, individuals involved in MTCs were prevalently Italian (72.7% vs 30.9%, p<0.001), male (82.9% vs 62.3%, p<0.001) and men who have sex with men (MSM) (43.5% vs 14.5%, p<0.001). Individuals in MTCs were also younger (median (IQR) years: 41 (35–49) vs 43 (36–51), p<0.001) and had higher CD4 cell count in comparison with individuals out of MTCs (median (IQR): 109/L: 0.4 (0.265–0.587) vs 0.246 (0.082–0.417), p<0.001). The viral load remained stable between the two groups (median (IQR) log10 copies/mL: 4.8 (4.2–5.5) vs 5.0 (4.3–5.5), p=0.87). Logistic regression confirmed that certain factors such as being MSM, of Italian origin, younger age and higher CD4 cell count were significantly associated with MTCs.
Conclusions Our findings show that HIV-1 newly diagnosed individuals infected with non-B subtypes are involved in several MTCs in Italy. These MTCs include mainly Italians and MSM and highlight the complex phenomenon characterising the HIV-1 spread. This is important especially in view of monitoring the HIV epidemic and guiding the public health response.
- transmission dynamics
- molecular epidemiology
- virology HIV
- transmission networks
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Handling editor Anna Maria Geretti
Presented at The manuscript was in part presented as a poster presentation at the 16th European Meeting on HIV & Hepatitis, 30 May–1 June 2018, Rome, Italy (Abstract 43).
Correction notice This article has been corrected since it published Online First. The authors noticed some minor textual errors in the paper which have been rectified now.
Collaborators The SENDIH (Studio Epidemiologico Nuove Diagnosi Infezione HIV-1) Study Group includes members at the following institutions: National Institute for Infectious Diseases, "Lazzaro Spallanzani" - IRCCS, Rome, Italy: Enrico Girardi, Maria Rosaria Capobianchi, Carlo Federico Perno, Nicoletta Orchi, Assunta Navarra, Antonio Palummieri, Isabella Abbate, Adriana Ammassari, Gabriella De Carli, Federica Forbici, Caterina Gori, Susanna Grisetti, Giuseppina Nurra, Carmela Pinnetti, Silvia Pittalis, Vincenzo Puro and Catia Sias; HIV/STI Unit, Clinical and Experimental Dermatology Department, San Gallicano Dermatological Institute IRCCS, Rome, Italy: Massimo Giuliani; Department of Public Health and Infectious Diseases, ‘Sapienza’ University, Rome, Italy: Vincenzo Vullo, Mario Falciano and Claudio Maria Mastroianni; Infectious Diseases, S Andrea Hospital, Sapienza University of Rome, Rome, Italy: Alfredo Pennica; UO AIDS ASL RMB S Pertini Hospital, Rome, Italy: Francesca Errigo; UO AIDS ASL RME, Rome, Italy: Laura Spizzichino; UO AIDS ASL RMD GB Grassi Hospital, Rome, Italy: Sergio Schito; Clinical Infectious Diseases, Fondazione Policlinico "Tor Vergata" University Hospital, Rome, Italy: Massimo Andreoni and Loredana Sarmati; Department of Experimental Medicine, University of Rome "Tor Vergata", Rome, Italy: Lavinia Fabeni; Infectious Diseases Unit, "Sapienza" University, Santa Maria Goretti Hospital, Latina, Italy: Miriam Lichtner and Vito S Mercurio; CRAIDS Hospital, Frosinone, Italy: Enza Anzalone; CRAIDS Hospital, Rieti, Italy: Antonella Pitorri; CRAIDS Hospital, Viterbo, Italy: Stefano Aviani Barbacci.
Contributors LF, CA and MMS conceived and designed the study. LF, CA, GB, RS, AB, LC, CG and FF planned and conducted the laboratory aspects of the study. NO, GDC, AV, RG, SC, AM, CP, LM, OT, MC, VB, FM, AP, ML, EG, MA, CM and AA collected the data. LF analysed the data, with support from CA and MMS. LF wrote the paper, with support from CA, MMS, FCS and CFP. All authors read and approved the final manuscript.
Funding This work was financially supported by the Italian Ministry of Education, University and Research (MIUR) (Bandiera InterOmics Protocollo PB05 1°) and an unrestricted grant from Aviralia Foundation.
Disclaimer The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the ethics committee of 'Tor Vergata' Hospital (Ethics Approval No 238/16, 14 December 2016). The SENDIH (Studio Epidemiologico Nuove Diagnosi Infezione HIV-1) study was approved by the ethics committee of the L Spallanzani National Institute for Infectious Diseases in 2003 (Ethics Approval N° 51, 18 December 2003). The research was conducted on anonymous samples in accordance with the principles of the Declaration of Helsinki and the Italian Ministry of Health. All information, including virological and clinical data, was recorded in an anonymised database.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.
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